A common oil well pumping system includes a walking beam mounted upon a horizontally-axised, transverse pivot at the top of a Samson post. One end of the walking beam is connected to a pump rod and the other end is connected to the crank of a drive motor through a connecting rod. Rotation of the crank causes the walking beam to rock or oscillate in a vertical plane to raise and lower the pump rod. The rod-connected end of the walking beam is provided with the familiar “horse head” to keep the pump rod in alignment with the well axis. The opposite end of the walking beam carries a counterbalance weight to offset the weight of the pump rod and minimize the stress on the motor.
When pumping an oil well, both oil and gas may be produced and the capture of the gas is both profitable and better for the environment. Thus, an oil well pumping system can include a compressor unit mounted between the walking beam and a stationary part of the pumping unit for compressing the natural gas produced during the pumping of the oil. Such a compressor unit is called a walking beam compressor because it has a piston rod that is coupled to the walking beam. Rocking of the walking beam reciprocates the piston rod to effect intake and compression strokes. Over time, due to the reciprocating motion, the connection between the piston rod and the walking beam can weaken or break. This can cause two problems. First, as the piston rod loosens, the piston rod stroke length within the compressor changes. The additional stroke length can cause the piston to bottom out against the bottom of the compressor, damaging both the compressor and the piston assembly. Second, the piston rod will eventually become completely detached from the walking beam. This may cause the compressor and piston rod to fall away from the walking beam, resulting in costly damage and possibly a dangerous situation.
Accordingly, there is a need for methods and devices that can effectively secure a piston rod to a walking beam of an oil well pump.